Process for colloiding nitrocellulose



United States Patent Ofiiice 3,037,247 Patented June 5, 1962 3,037,247 PROCESS FOR COLLOIDING NITROCELLULOSE Ralph F. Preckel, Cumberland, Md., assignor to'Hercules Powder Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Dec. 24, 1954, Ser. No. 477,585 20 Claims. (Cl. 1855) This invention relates to the treatment of nitrocellulose and more particularly to the colloiding of nitrocellulose and the production of smokeless powder.

Currently, smokeless powder is prepared either by the solvent process, by solventless extrusion, or by a casting procedure. In the classic solvent process, nitrocellulose is dissolved in or colloided by the addition thereto of a volatile solvent such as acetone, ether-alcohol, acetone-alcohol, and the like, and by mixing the nitrocellulose and solvent until a viscous mass is obtained. This mass is then granulated by suitable means and volatile solvent is removed as completely as possible. While this process has been standard for many years, it has always been recognized that the amount of time taken to extract solvent from the grains is undesirably great. Moreover, certain hazards are connected with the use of volatile solvents and these solvents themselves are subject to uneconomic loss by evaporation unless costly solvent recovery processes and equipment are employed. In addition, it is a known fact that the volatile solvent, because of its great afiinity for the nitrocellulose, is never completely removed from the grains in any practical drying time and that even in the small granulations, residual solvent migration results in a change in the ballistics of the powder. As a general rule, the solvent process is not used where a powder web of greater than 0.5 inch is desired.

Because of these undesirable aspects of the solvent process, the solventless extrusion techniques were developed. -In the conventional solventless extrusion method the desired powdered ingredients are mixed in the presence of water. The resulting paste or slurry is then dried to the desired moisture content and the resulting mass is rolled on hot rolls to obtain a colloided sheet. This sheet is then extruded into the desired granulation. While it has been necessary to employ this process in place of the solvent process where a powder web of greater than about /2 inch is desired, it has always been recognized that solventless extrusion is an inherently hazardous process due to the constant possibility of fire and even detonation during colloiding of the composition in the oiling and extrusion steps. In addition, poor quality is ften caused in the extruded grains by air which is trapped ifliiin the charge prior to extrusion. Moreover, a large nt of manual handling is involved unless very costly t atic equipment is employed, thus in either case rendering the solventless extrusion process relatively expensive.

When even larger powder grains with even thicker webs begamg desirable for use in rockets and in JATO units, it was e nized at once that due to the massive nature of the extrusion presses which would be necessary to produce large grains and the danger involved from pressing large quantities of solventless composition, the solventless extrusion" process was unsatisfactory. Consequently, several casting techniques have been developed in which tiny grains, usually manufactured by the solvent process, are introduced into a mold, together with the desired explosive and nonexplosive, nonvolatile plasticizers, and the grain of the desired size is cast through the solvation of the granules by the plasticizer. However, in order to produce the cast grain in this manner, it is necessary to accept the disadvantages of either the solvent" or solventless extrusion processes in the production of the base grain to be used in the casting operation.

Now in accordance with the present invention, a process has been discovered which makes possible the colloiding of nitrocellulose in general and the production of smokeless powder without the use of volatile solvents and without the necessity of hot roll colloiding. In some embodiments of the process of the invention, and particularly those directed to the production of small grain smokeless powder, a pressing operation is also completely unnecessary.

Generally described, the process of the invention comprises introducing a solution comprising at least one watermiscible alkoxy alcohol and at least 1% of nitrocellulose having a percent N of at least 11.3 into a water bath containing at the point of initial contact not more than of the alkoxy alcohol to gel the solution, leaching the gelled material in the presence of water until a predetermined amount of the alkoxy alcohol in the material has been replaced by water and subjecting the material to drying conditions to remove Water and produce a colloided nitrocellulose body. In the process described, the surface of the nitrocellulose introduced into the bath is gelled at the instant of contact and a tough envelope of nitrocellulose composition is formed about the exterior of the body. This envelope is of suflicient toughness that the body retains its shape. As the shock gelled particle is retained in the bath or otherwise further contacted with the aqueous medium, the water continues to leach the alkoxy alcohol from the particle and the water may continue to take the place of the alkoxy alcohol until an equilibrium is approached. Thus, in a batch process a solution of given concentration of nitrocellulose in the alkoxy alcohol will be gelled when introduced into the water bath, and the amount of alkoxy alcohol removed from the gelled composition will depend upon the concentration of alkoxy alcohol in the water bath and the time of contact. If the process is conducted stepwise and the gelled material is progressively introduced into fresh baths of lower alkoxy alcohol concentrations, the point will be reached at which substantially all of the alkoxy alcohol will be removed and a highly pure, fully colloided nitrocellulose is obtained. In a continuous process the gelled material may be progressively contacted with solution containing less and less of the alkoxy alcohol and discharged in a substantially alkoxy alcohol free condition while concentrated alkoxy alcohol is withdrawn at one point in the process and water is continuously added at another.

The solution of nitrocellulose and alkoxy alcohol may be introduced into the gelling bath in a number of ways. In the production of small particles it is preferred that the solution of nitrocellulose and alkoxy alcohol be formed into droplets of the desired size by passage through a perforated plate. The droplets thus formed are preferably allowed to fall freely until they assume a spherical or spheroidal configuration prior to contacting the bath. Upon striking the surface of the bath, the gelation of the surface of such particles is so rapid that no substantial distortion occurs. Alternatively, the solution may be sprayed from a suitable nozzle or gun and the particles thus formed are allowed to fall into the gelling bath. If desired, the particles may first be allowed to fall through a mist of the gelling medium to initiate surface gelation. When employing either of these two techniques, it is preferred to employ a nitrocellulose concentration in the solution of between 1% and The solution may also be introduced into the bath by gravity or low pressure extrusion. In accordance with this technique a solution, preferably characterized by a nitrocellulose concentration of between 1% and is allowed to run through an orifice of the desired size into the gelling bath. The resulting gelled material will be cordlike and can be processed and cut in the desired granulation as in the conventional solvent technique.

In yet another embodiment of the invention a system can be formed which contains from 20% to 70% or more of nitrocellulose. This composition will be characterized by a viscosity similar to that of the solvent paste employed in the conventional solvent process and may be extruded in the conventional manner, cut in predetermined lengths, and then introduced into the water bath for gelation and removal of the alkoxy alcohol solvent.

In all of these techniques the gelled particle uniformly shrinks as the water is removed in the drying operation to final dimensions determined by the original concentration of nitrocellulose in the solution which is gelled.

The conventional additives to nitrocellulose and smokeless powder compositions may be added at various points in the process without detracting from the method as hereinabove set forth. For example, plasticizers and other additives such as stabilizers and ballistic modifiers for the nitrocellulose may be incorporated in the original solution, thus giving a finished particle in which the plasticizers and additives are uniformly incorporated. Alternatively, the plasticizers may be introduced into the grain or particle after their removal from the gelling bath as, for example, by contacting the waterlogged particles with an aqueous solution, suspension or emulsion of the plasticizer or additive for a period necessary to obtain the desired degree of absorption. In general, it is preferred to introduce only substantially water-insoluble plasticizers and additives into the original solution prior to the gelation step. In most instances it is probably not desirable to incorporate such plasticizers as liquid explosive nitric esters, pentaerythritol trinitrate or dimethylphthalate in the original solution, since even their limited water solubility causes a leaching of an undesirable amount of the plasticizers from the gelled particles along with the alkoxy alcohol solvent. For such materials, it is preferred to employ the alternate method of incorporation. For example, the waterlogged particles may be removed from. the gelling bath and then introduced into an emulsion of nitroglycerin and water and maintained therein, preferably with agitation, until the desired amount of nitroglycerin is absorbed by the nitrocellulose. Then, when subjected to the drying operation, the residual water is removed and a colloided double base propellant body is obtained. As will be subsequently discussed, nonplasticizers for nitrocellulose may also be introduced into the nitrocellulose structure to produce compositions having novel and desirable properties.

The waterlogged particles or bodies with or without plasticizer may be dried by conventional means and processes. However, in view of the fact that water is not a solvent for nitrocellulose, it is removed much more rapidly than the volatile solvents employed in the solvent process. It has been found that where many days are required to remove a volatile solvent from a grain of a given size only a few hours are required to remove the water from the gelled bodies formed in accordance with the invention. Preferably, the water is removed by placing the waterlogged particles in a tray having a foraminous bottom and forcing hot air upwardly through the particles. Preferably, air velocities are used which cause the particles to become fluidized. The most rapid drying times have been obtained with such a procedure. It is within the scope of the invention, however, that conventional dry house techniques, infrared radiation and other conventional processing be employed in the drying procedures.

The operable alkoxy alcohols include, without limitation, diethylene glycol, polyethylene glycoi, dipropylene glycol, polypropylene glycol, methoxyethanol (methyl Cellosolve), diethylene glycol methy lether (methyl carbitol), glyceryl-a-allylether and glyceryl-a-methylether. Mixtures of the operable alkoxy alcohols may also be employed and in some cases are preferred,

In view of the fact that the solubility characteristics of nitrocellulose depend upon the percent nitrogen of the nitrocellulose, all nitrocellulose cannot be dissolved in every one of the alkoxy alcohols to the same concentration and in most instances nitrocellulose is not soluble in one particular solvent throughout the entire nitration range. However, the solubility of a particular grade of nitrocellulose in a particular solvent is a strictly physical phenomenon and the selection of the preferred solvent or solvent mixtures to be employed in the present invention is a routine matter. In Table 1, data are presented showing alkoxy alcohols or mixtures in which the indicated nitrocellulose was dissolved and the resulting solutions were gelled to produce, after leaching and drying, excellent colloided nitrocellulose bodies. The table does not represent limits of solubility but instead preferred alkoxy alcohols for nitrocellulose of specific percent N.

Of all the alkoxy alcohols, diethylene glycol is preferred, especially when employed with nitrocellulose having a percent N of between 12 and 13.

Having generally described the invention, the following examples are presented to illustrate specific embodiments. In the examples all parts are by weight unless otherwise indicated.

Example 1 Ten parts of nitrocellulose (12.6% N) was dissolved in parts of diethylene glycol. This solution was exftruded through a glass tube by means of squeezing a sol-ntion-filled rubber bulb attached to one end of the tr be 0.25 inch in inside diameter. The egress end of thetube was placed under the liquid surface of a water bath o that the strand of solution was delivered under water, The solution gelled immediately on contact with the wat d appeared to take approximately the diameter of the inside diameter of the tube. The resulting strand wa allo ed to remain in the bath for 16 hours at which time it was removed and dried to remove the water. A fully colloided nitrocellulose strand 0.1 inch in diameter was obtained.

Example 2 Five parts of nitrocellulose (12.6% N) was dissolved in 95 parts of diethylene glycol. This solution was poured into a metal container, the bottom of which contained perforations about .09 inch in diameter. The droplets of solution emitting from these holes were allowed to fall about 18 inches through the air before striking the surface of a water bath. During this fall the droplets became essentially spherical. The surfaces of the droplets gelled instantly upon contact with the water bath and were stifliciently tough to withstand passage through the water surface without substantial deformation. The halls thus produced were leached in running water for a period of two hours, at which time they were about .15 inch in diameter. The waterlogged balls were removed from the water and dried overnight at a temperature of 60 C. The resulting fully colloided spherical nitrocellulose balls were .05 inch in diameter.

The compositions set forth in Examples 3, 4 and 5 were prepared and extruded into the gelling bath. The resulting strands were completely leached with water, run through a conventional cutting machine and then dried to produce a product in all respects the substantial ballistical equivalent to that produced by the normal volatile solvent process. The compositions were extruded at a pressure of psi through a die .06 inch in diameter to give initial strands of wet diameter about .075 inch which, when dried, had a final diameter of .035 inch.

Example 3 Nitrocellulose (12.6 %N) 8.8 Dioctyl phthalate 0.5 Nitrodiphenylamine 0.2 Lead stearate 0.5 Diethylene glycol 90.0

Example 4 Nitrocellulose (12.6% N) 8.8 Dioctyl phthalate 0.5 Nitrodiphenylamine 0.2 Lead salicylate 0.5 Diethylene glycol 90.0

Example 5 Nitrocellulose (12.6% N) 8.8 Dioctyl phthalate 0.7 Lead salicylate 0.3 Nitrodiphenylamine 0.2 Diethylene glycol 90.0

Example 6 A solution was made of the following components: Nitrocellulose (12.6% N) 4.4 Dioctyl phthalate 0.25 Lead stearate 0.25 Nitrodiphenylamine 0.1 Diethylene glycol 95.0

This solution was allowed to flow through .09 inch holes in a metal container and into a water bath as described in Example 2. The resulting spheroids were leached for a period of 2 hours and dried for 16 hours at 60 C. to give a final product having a diameter of about .05 inch. This powder was employed in the normal manner to prepare a cast propellant. The resulting casting exhibited substantially the same ballistic performance as a casting of the same composition made in the same manner from base grains formed by the solvent process. In producing the powder employed in this example, the water bath was maintained at a temperature of 60 C. to speed up the leaching operation.

Example 7 The solution of Example 6 was introduced in increments of about 1 fluid ounce each into a layer of mineral oil floating on a water bath. The blob of solution be came spheroidal upon passing through the oil-water interface and was gelled in the normal fashion. The initial gelled ball formed was 1.5 inches in diameter. When these balls were exposed to fresh water until the diethylene glycol was completely leached therefrom and were then dried, fully colloided spherical balls of nitrocellulose 0.5 inch in diameter were obtained.

Example 8 One part of nitrocellulose (13.4% N) was dissolved in 99 parts of polyethylene glycol (200 M.W.). This solution was poured through a plate having perforations .09 inch in diameter into a water bath. The resulting gelled balls were leached for 2 hours and dried at C. as above described to produce normal colloided nitrocellulose.

Example 9 Seven parts of nitrocellulose (13.4% N) was dissolved in 93 parts of methoxyethanol. This solution was poured through a perforated plate into an aqueous solution containing methoxyethanol. The droplets gelled instantly upon contact with the gelling bath and following leaching for 2 hours and drying for 16 hours at 60 C. gave completely colloided nitrocellulose spheroids.

Example 10 Seven parts of nitrocellulose (13.9% N) was dissolved in 93 parts methoxyethanol and was poured through a perforated plate into an aqueous gelling bath containing 65% rnethoxyethanol. The resulting spheroids were leached for 2 hours and dried at 60 C. for 16 hours to produce fully colloided nitrocellulose particles.

Example 11 Twenty parts of nitrocellulose (12.1% N5 sec. RS) was dissolved in parts of diethylene glycol. The resulting solution was extruded through a die .051 inch in diameter, water leached for 2 hours and then cut into grains .036 inch long. The water was removed from these grains by drying 16 hours at 60 C. to produce fully colloided grains of nitrocellulose.

Example 12 Ten parts of nitrocellulose (12.0% N21 cp.) was dissolved in parts of diethylene glycol and the resulting solution was poured through perforations .09 inch in diameter into a water bath. The resulting gelled balls were water leached for 2 hours and then dried for 16 hours at 60 C. to produce fully colloided nitrocellulose.

Example 13 Seven parts of nitrocellulose (13.2% N) was dissolved in 93 parts of a mixture of equal parts of diethylene glycol and methoxyethanol. This solution was poured through a perforated plate (perforations .09 inch in diameter) into water. The resulting gelled spheroids were leached and dried to produce completely colloided nitrocellulose.

Example 14 A solution was formed from 3.6 parts nitrocellulose (12.6% N), 4.3 parts pentaerythritol trinitrate and 92.1 parts diethylene glycol. This solution was poured through a perforated plate (perforations .09 inch in diameter) into a water bath, gelled, leached for 2 hours and dried for 16 hours at 60 C. to produce a plasticized nitrocellulose composition containing 10.7% pentaerythritol trinitrate.

Example 15 A solution was formed from 4.9 parts nitrocellulose (12.6% N), 2.2 parts nitroglycerin and 92.9 parts diethylene glycol. This solution was poured through a plate containing perforations .09 inch in diameter into a water bath. The gelled, leached (4 hours) and dried (16 hours at 60 C.) composition gave a colloided, double base smokeless powder containing 13.8% nitroglycerin, indicating that about 60% of the nitroglycerin had been lost to the water phase.

Example 16 A solution was prepared from parts nitrocellulose (12.6% N), 3 parts nitroglycerin and 92 parts diethylene glycol. The process of Example 15 was repeated except that the leaching time in the water bath was decreased to 2 hours. The dry product obtained contained 73% nitrocellulose, 22.2% nitroglycerin and 4.8% residual diethylene glycol. In this example, about 50% of the nitroglycerin was lost to the water phase.

Example 17 T hirty-nine and one-half parts of nitrocellulose (12.6% N), 0.5 part of nitrodiphenylamine and 60 parts of diethylene glycol were introduced into a standard sigmoid dough mixer and mixed until a homogeneous dough was obtained. The doughy mass was then extruded in a hydraulic press through a die .051 inch in diameter, giving well colloided strands of green powder. These strands were then gelled by being introduced into a water bath and leached for 2 hours to remove the diethylene glycol. The waterlogged strands were then dried for 16 hours at 60 C. to give completely colloided nitrocellulose.

Example 18 A solution was formed from 4.75 parts nitrocellulose (12.6% N), .1 part nitrodiphenylamine, .15 part of lead stearate and 95 parts of diethylene glycol. This solution was gelled by being poured through a plate containing perforations .09 inch in diameter into a water bath and leached for 2 hours. The waterlogged balls were then removed from the gelling bath and agitated in a dilute water solution of dimethylphthalate (DMP concentration of 0.3%). After several hours of agitation, the balls were removed from the bath and dried for 16 hours at 60 C. to produce a product containing 91.5% nitrocellulose, 1.8% nitrodiphenylamine, 2.8% lead stearate and 4.8% dimethylphthalate.

Example 19 A solution was formed from 3.1 parts nitrocellulose (12.6% N) and 95.5 parts diethylene glycol. This solution was gelled by pouring through a perforated plate (perforations .09 inch in diameter) into a water bath and leaching for 2 hours to remove the diethylene glycol. Eighty-nine parts of the waterlogged balls were introduced into 50 parts of a 4% nitroglycerin aqueous emulsion and stirred for six hours. After the water had been removed from the balls by drying for 16 hours at 60 C., the resulting dry double base propellant spheres contained 64.4% nitrocellulose and 35.6% nitroglycerin.

Example 20 A solution was formed from 6.1 parts nitrocellulose (12.6% N), 0.4 part of dimethylphthalate, 0.2 part nitrodiphenylamine, 0.3 part lead stearate and 89.9 parts diethylene glycol. This solution was gelled and the gelled balls were leached as in Example 19. Forty parts of the water-wet balls were stirred in 500 parts of 0.8% nitroglycerin aqueous emulsion for six hours and then were removed and dried. The resulting double base propellant spheres contained 63.1% nitrocellulose, 2.8% dimethylphthalate, 1.4% nitrodiphenylamine, 2.1% lead stearate and 30.6% nitroglycerin.

Example 21 The operation described in Example 20 was repeated except that in this case the nitroglycerin emulsion was at 0.4% concentration. The double base smokeless powder obtained contained 62.5% nitrocellulose, 0.3% dimethylphthalate, 1.5% nitrodiphenylarnine, 2.0% lead stearate and 31.0% nitroglycerin. In this case about of the nitroglycerin present was absorbed by the powder.

Example 22 Water-wet balls of straight nitrocellulose were prepared by gelling, as above described, a solution of nitrocellulose (12.6% N) and diethylene glycol, 4.5/95.5. One hundred parts of the water-wet balls were immersed for six hours in 50 parts of a 4% aqueous emulsion of glycol dinitrate. The resulting double base spheres contained 79% nitrocellulose and 21% glycol dinitrate.

Example 23 Waterlogged balls of nitrocellulose were obtained by gelling, as above described, a solution of 5 parts nitrocellulose (12.6% N) and parts diethylene glycol. Eighteen hundred parts of the leached, waterlogged balls were then immersed in a solution containing 22.1 parts of lead acetate in 4000 parts of water for five hours. The balls were then removed from the solution and dried for 20 hours at 60 C. The resulting product contained 95.6% nitrocellulose and 4.4% lead acetate.

Example 24 Seven parts of nitrocellulose (11.3% N) was dissolved in parts of glycerol-a-allylether. The solution was poured through a perforated plate having perforations .09 inch in diameter and into a water bath. The gelled droplets thus formed were leached in the water for 2 hours and the waterlogged balls were dried for 16 hours at 60 C. Fully colloided nitrocellulose balls were obtained.

Example 25 Spherical nitrocellulose balls .05 inch in diameter produced in accordance with the invention were loaded in centerfire .30-06 caliber cartridges. With a 172 grain bullet and a charge of 43 grains, a velocity of 2597 ft./sec. was obtained at a pressure of 48,000 p.s.i. These ballistics establish that the powder produced in accordance with the invention is at least equivalent in performance to currently standard powders used in the .30-06 cartridge.

From the foregoing examples it will be seen that smokeless powder compositions, either single or double base, containing desired additives and/ or plasticizers, both Water-soluble and water-insoluble, can readily be prepared in accordance with the process of the invention. While many advantages of this process over the prior art processes will be noted, the process of the invention is especially noteworthy in the elimination of safety hazards connected with the use of volatile solvents, the elimination of uneconomic losses of volatile solvent through evaporation, the freedom from the hazards of hot rolling colloiding steps and the radical shortening of processing time. As has been illustrated, a finished powder can be prepared in only a few hours by the process of the invention as compared to the many days necessary in prior art volatile solvent processes. In the process of the invention, the nitrocellulose is always kept in a relatively nonhazardous condition since it may be employed wet with as much as 20% to 30% water. In fact, the system employed never app-roaches the hazards of the conventional solvent process, except at the very end of the drying cycle and even then an antistatic graphite glaze may already have been applied if desired.

Recovery of the alkoxy alcohol from the gelling bath is less complicated than the volatile solvent recovery systems necessary in conventional processes. For the higher boiling alkoxy alcohols, such as diethylene glycol, a vacuum stripping column is preferred in which the pressure during distillation is maintained at about 20 mm. For the lower boiling alkoxy alcohols, it is preferred to employ a simple fractionating column of not more than five or six theoretical plates for the lowest boilers.

Since one of the primary objects of this invention is an improved process for the production of smokeless propellants, the majority of the examples employed to illustrate the process have been conducted with pyro grade nitrocellulose (12.6% N). However, the applicability of the process to the wide range of nitrocellulose containing above 11.3% N has been illustrated.

As is apparent, the process is not limited to the production of smokeless powder but obviously can be employed in the production of molding powder and preparation of shaped nitrocellulose bodies as may be desired. For example, the leached, waterlogged body may be introduced into a water-miscible organic nonsolvent for nitrocellulose, such as ethyl, tert-butyl, propyl, or isopropyl alcohol and the water replaced. Then the resulting system may be introduced into a nonsolvent for nitrocellulose which is miscible with the water-miscible liquid now supporting the nitrocellulose structure, such as toluene, benzene or Xylene. This liquid support may now be similarly completely replaced with a nonvolatile, water-immiscible liquid or molten substance which is a nonsolvent for nitrocellulose such as mineral oil, polyphenyl, tristearin, tripalmitin and the like to produce a tough, rugged, elastic, fully colloided nitrocellulose plastic composition characterized by surprisingly high strength and impact resistance. These compositions h. ve utility in such applications as tool handles, golf balls, hammer or mallet heads, accessory knobs, handles and the like, permanently lubricated light duty ball, roller or sleeve bearings, flooring, wallboard, tile and the like. Fully colloided nitrocellulose sheets and films have also been produced by the process of the invention. These sheets may be flaked to produce propellant, molding powder, or other useful particulate nitrocellulose or nitrocellulose compositions.

Since various ramifications of the process will be apparent to those skilled in the art, the invention will be limited by the scope of the appended claims.

What I claim and desire to protect by Letters Patent is:

1. A process for colloiding nitrocellulose which comprises preforming a solution comprising at least one water miscible alkoXy alcohol and at least 1% of nitrocellulose having a percent N of at least 11.3, introducing the preformed solution into a water bath containing at the point of initial contact not more than 90% of the alkoxy alcohol to rapidly gel the surface thereof so that no substantial distortion of the gelled material thus formed occurs, leaching the gelled material in the presence of additional water until substantially all of the alkoxy alcohol in the material has been replaced by water and said material has become waterlogged, and subjecting the waterlogged material to drying conditions to remove water and produce a colloided nitrocellulose.

2. A process according to claim 1 in which the solution is poured through a perforated plate and the droplets thus formed are allowed to fall into the bath.

3. A process according to claim 1 in which the solution is gravity extruded into the bath.

4. A process according to claim 1 in which the solution is pressed through an orifice and introduced into the bath.

5. A process for colloiding nitrocellulose which comprises preforming a solution comprising at least one water-miscible alkoxy alcohol, at least 1% of nitrocellulose having a percent N of at least 11.3 and a. plasticizer for nitrocellulose, introducing the preformed solution into a Water bath containing at the point of initial con tact not more than 90% of the alkoxy alcohol to rapidly gel the surface thereof so that no substantial distortion of the gelled material thus formed occurs, leaching the gelled material in the bath with additional water until substantially all of the alkoxy alcohol in the material has been replaced by water and said material has become waterlogged, and subjecting the waterlogged material to drying condiions to remove the residual water and produce a colloided nitrocellulose composition.

6. A process according to claim 5 in which the solutions is poured through a perforated plate and the droplets thus formed are allowed to fall into the bath.

7. A process according to claim 5 in which the solution is gravity extruded into the bath.

8. A process according to claim 5 in which the solution is pressed through an orifice and introduced into the bath.

9. A process for colloiding nitrocellulose which comprises preforming a solution comprising at least one water-miscible alkoxy alcohol and at least 1% of nitrocellulose having a percent N of at least 11.3, introducing the preformed solution into a water bath containing at the point of initial contact not more than of the alkoxy alcohol to rapidly gel the surface thereof so that no substantial distortion of the gelled material thus formed occurs, leaching the gelled material in the presence of additional water until substantially all of the alkoxy alcohol in the material has been replaced by water and said material has become waterlogged, removing the leached and waterlogged material from the bath and contacting said material in aqueous emulsion with a plasticizer for nitrocellulose, separating the plasticized and waterlogged material from the aqueous phase and subjecting said material to drying conditions to remove residual water and produce a colloided nitrocellulose composition.

10. A process according to claim 9 in which the solution is poured through a perforated plate and the droplets thus formed are allowed to fall into the bath.

11. A process according to claim 9 in which the solution is gravity extruded into the bath.

12. A process according to claim 9 in which the solution is pressed through an orifice and then introduced into the bath.

13. A process for manufacturing smokeless powder which comprises dissolving at least 1% of a nitrocellulose having a percent N of between 12 and 13 in diethylene glycol, preforming the resulting solution and introducing it into an aqueous bath containing not more than 90% diethylene glycol at the point of original contact to rapidly gel the surface thereof so that no substantial distortion of the gelled material thus formed occurs, leaching the gelled material in the presence of additional water until substantially all of the diethylene glycol in the material has been replaced by water and said material has become waterlogged, and subjecting the waterlogged material to drying conditions to produce a colloided smokeless powder.

14. A process according to claim 13 in which the solution is poured through a perforated plate and the droplets thus formed are allowed to fall into the bath.

15. A process according to claim 13 in which the solution is gravity extruded into the bath.

16. A process according to claim 13 in which the solution is pressed through an orifice and then introduced into the bath.

17. A process for manufacturing smokeless powder which comprises dissolving at least 1% of a nitrocellulose having a percent N of between 12 and 13 and a substantially water-insoluble nonexplosive plasticizer for the nitrocellulose in diethylene glycol, preforming the resulting solution and introducing it into an aqueous bath containing not more than 90% diethylene glycol at the point of original contact to rapidly gel the surface thereof so that no substantial distortion of the gelled material thus formed occurs, leaching the gelled material in the presence of additional water until substantially all of diethylene glycol in the material has been replaced by water and said material has become waterlogged, removing the gelled and waterlogged material from the bath and contacting it in aqueous suspension with liquid explosive nitric ester until a predetermined amount of ester has been absorbed by said material, discontinuing contact with the emulsion and subjecting the ester absorbed and waterlogged material to drying conditions to remove residual water and produce a fully colloided double base smokeless powder.

18. A process according to claim 17 in which the solution is poured through a perforated plate and the droplets thus formed are allowed to fall into the bath.

19. A process according to claim 17 in which the solution is gravity extruded into the bath.

20. A process according to claim 17 in which the solution is pressed through an orifice and then introduced into the bath.

References Cited in the file of this patent UNITED STATES PATENTS Davidson June 28, 1927 Moran Aug. 30, 1927 Lowry Feb. 11, 1930 Davidson Nov. 19, 1935 Graves May 24, 1938 Boddicker Jan. 9, 1940 Aaron et al Jan. 28, 1941 

1. A PROCESS FOR COLLOIDING NITROCELLULOSE WHICH COMPRISES PREFORMING A SOLUTION COMPRISING AT LEAST ONE WATER MISCIBLE ALKOXY ALCOHOL AND AT LEAST 1% OF NITROCELLULOSE HAVING A PERCENT N OF AT LEAST 11.3, INTRODUCING THE PREFORMED SOLUTION INTO A WATER BATH CONTAINING AT THE POINT OF INITIAL CONTACT NOT MORE THAN 90% OF THE ALKOXY ALCOHOL TO RAPIDLY GEL THE SURFACE THEREOF SO THAT NO SUBSTANTIAL DISTORTION OF THE GELLED MATERIAL THUS FORMED OCCURS, LEACHING THE GELLED MATERIAL IN THE PRESENCE OF ADDITIONAL WATER UNTIL SUBSTANTIALLY ALL OF THE ALKOXY ALCOHOL IN THE MATERIAL HAS BEEN REPLACED BY WATER AND SAID MATERIAL HAS BECOME WATERLOGGED, AND SUBJECTING THE WATERLOGGED MATERIAL TO DRYING CONDITIONS TO REMOVE WATER AND PRODUCE A COLLOIDED NITROCELLULOSE. 